When you are buying new shoes and lacing them for the first time you might have wondered why the upper part of the shoe sometimes have two holes. I've wondered that, but I've never thought about finding out why there are two holes. Today I found a video explaining exactly that. Apparently, if you are using the second hole (in the way described in the video below), it will prevent blisters. This technique is called a "Heel Lock" or "Lace Lock."